Docs: examples with arrow functions in no-return-assign (fixes #13135) (

#13138)

* Chore: docs example for arrow function and tests (fixes #13135)

* Chore: removed wrong test case

* Chore: refactore snipper and added tests

docs/rules/no-return-assign.md

@@ -40,6 +40,14 @@ function doSomething() {
 function doSomething() {
     return foo += 2;
 }
+
+const foo = (a, b) => a = b
+
+const bar = (a, b, c) => (a = b, c == b)
+
+function doSomething() {
+    return foo = bar && foo > 0;
+}
 ```
 
 Examples of **correct** code for the default `"except-parens"` option:
@@ -58,6 +66,14 @@ function doSomething() {
 function doSomething() {
     return (foo = bar + 2);
 }
+
+const foo = (a, b) => (a = b)
+
+const bar = (a, b, c) => ((a = b), c == b)
+
+function doSomething() {
+    return (foo = bar) && foo > 0;
+}
 ```
 
 ### always

tests/lib/rules/no-return-assign.js

@@ -52,6 +52,19 @@ ruleTester.run("no-return-assign", rule, {
         {
             code: "() => (result = a * b)",
             options: ["except-parens"]
+        },
+        "const foo = (a,b,c) => ((a = b), c)",
+        `function foo(){
+            return (a = b)
+        }`,
+        `function bar(){
+            return function foo(){
+                return (a = b) && c
+            }
+        }`,
+        {
+            code: "const foo = (a) => (b) => (a = b)",
+            parserOptions: { ecmaVersion: 6 }
         }
     ],
     invalid: [
@@ -79,7 +92,12 @@ ruleTester.run("no-return-assign", rule, {
         },
         {
             code: "() => result = a * b",
-            errors: [{ messageId: "arrowAssignment", type: "ArrowFunctionExpression" }]
+            errors: [
+                {
+                    messageId: "arrowAssignment",
+                    type: "ArrowFunctionExpression"
+                }
+            ]
         },
         {
             code: "function x() { return result = a * b; };",
@@ -95,6 +113,68 @@ ruleTester.run("no-return-assign", rule, {
             code: "function x() { return result || (result = a * b); };",
             options: ["always"],
             errors: [{ messageId: "returnAssignment", type: "ReturnStatement" }]
+        },
+        {
+            code: `function foo(){
+                return a = b
+            }`,
+            errors: [{ messageId: "returnAssignment", type: "ReturnStatement" }]
+        },
+        {
+            code: `function doSomething() {
+                return foo = bar && foo > 0;
+            }`,
+            errors: [{ messageId: "returnAssignment", type: "ReturnStatement" }]
+        },
+        {
+            code: `function doSomething() {
+                return foo = function(){
+                    return (bar = bar1)
+                }
+            }`,
+            errors: [{ messageId: "returnAssignment", type: "ReturnStatement" }]
+        },
+        {
+            code: `function doSomething() {
+                return foo = () => a
+            }`,
+            parserOptions: { ecmaVersion: 6 },
+            errors: [
+                {
+                    messageId: "returnAssignment",
+                    type: "ReturnStatement"
+                }
+            ]
+        },
+        {
+            code: `function doSomething() {
+                return () => a = () => b
+            }`,
+            parserOptions: { ecmaVersion: 6 },
+            errors: [
+                {
+                    messageId: "arrowAssignment",
+                    type: "ArrowFunctionExpression"
+                }
+            ]
+        },
+        {
+            code: `function foo(a){
+                return function bar(b){
+                    return a = b
+                }
+            }`,
+            errors: [{ messageId: "returnAssignment", type: "ReturnStatement" }]
+        },
+        {
+            code: "const foo = (a) => (b) => a = b",
+            parserOptions: { ecmaVersion: 6 },
+            errors: [
+                {
+                    messageId: "arrowAssignment",
+                    type: "ArrowFunctionExpression"
+                }
+            ]
         }
     ]
 });